Electrical precipitator



Jan. 17, 1950 K. w. M 'KENZlE ELECTRICAL PRECIPITATORS 2 Sheets-Sheet 1Filed March 18, 1941 /NVENTO/? KENNGTH W MAcL avz/E Q 5v Jan. 17, 1950K. w. M KENzlE 2,494,822

ELECTRICAL PRECIPITATORS Filed March 18,1947 2 Sheets-Sheet 2 m C 0Q 0)M. a r h v a I L/ r 3;

I "4 I: w J b m m g g I! Q f m a Ln m N? 8 N N I H i m '5 N m \l A/NVENTOR A ENNETH W MACKENZIE E ATTDI'PNEV Patented Jan. 17, 1950ELECTRICAL. PRE GIPITATOR Kenneth. W; MacKenzie, Newton Highlands, Massassignor: to; Raytheon. Manufacturing. Gompany; Newton Mass;,acorporation of'Delaware.

Application March 18, 1947, Serial No. 735,403

Thisinvention relates-to electrical ,precipitators for; separatingparticulate matter from atmosa pheric-air, and moreparticularly to a:systemfor: controlling. the operation of? such. preclpitators'.

Electrical dust precipitators, of the: type inwhichthe air tobe cleanedis first ionized in an. ionizing; zone; where thedust particles receiveanelectrical charge; andisthen passed toacollecting zone Where thechargedparticles-am deposited. upon; suitable= collecting electrodes,must be cleaned. at: intervals; otherwisethe: accumulateddesposits=williinterierewith the operati'onoi the system. Where theprecipitator is intended for. use in a home or oth'erplace-Where'itwould be impractical to: employ: a skilled attendant formaintainingthe-system; it is desirable to limit the operations required of the userand. to-soasimplifythese that thepossibility of mistakes-and'misusewillbe minimized. In-mycopending application, Serial No; 713 221; filedNovember 30'; 1946; now- Patent No; 2,47 6,248, datediJuly 12; 1949,there shown an electrical. dust precipitat'or" suitable for' home use inwhich the: collecting electrodes may be washed in situ by afluidlspraylng meansassociated with thei system.-

The present invention contemplates the pro vision of a controlsystem-which will effect-the washing operation at: the Will'- of theoperator without requiring material attention or-timeon: the part of theoperator:

To these ends-it is an object-oi thisinventiom toprovide a controlsystem for precipitators of the type described, which maybeset: inoperation to eilect thecleaning process by the actuation ofa switch, andwhich will then effeot the required' operations .in thedesired-sequence-and' with the proper timing.

It is a'further-object' of the invention toprovide a control system ofthe=type-described which will insure that thepowersupply to the ionizingand collecting electrodes will bediscontinued prior to the initiation-ofthe supply of'cl'eaning-" fluid to the electrodes;

It is 1 a further obj ect of the inventiontoprovide.

a control-systemofthe type'described which=will' permit the staticchargeon the-preeipitator"elec trodes to be dissipatedprior-tothespraying of such electrodesw-ithcleaning 'fluid.

It is afurther object-of the' invention toprovide aconstruction in whichth-e powersupply'to the motorof Y the fair orequivalent means forforcingair through the-precipitatoris discon-' tinned during; the period"cleaning-fluid is sprayed" onptheprecipitatorgelectrodes; andin which;upon thetermination-oi-thesupplyof-claningflhid; the

7 Claims; (Cl. 183-7) fan. will force air: through. the precipitator.fora predetermined periodlprior to the energizationofthe. precipitatorelectrodes: to. entirely dry said electrodes before; the appearance-ofhighv voltages 1 therebetween.

In. some domesticrisystemsit. is desired: to. pro- Vide' a constructionin. which; th dust precipi. tatingi means is associated with. the"furnace, to

the endthat the. air tobepurifiedisfirst.forcedthrough. theprecipitating means: and thence.-

passed inheat absorbinggrelation; to; the furnace; thus providing. a.combined? air purifying and heating system.

Itis a further object of. the. presentinvention toprovide, in sucliza:combined system, a, control circuit. in which the"- fuelv supply to thefurnace and the control means icapable ofeff ectingsuch fuel supply aredeenergizediduring the per-iod'iniwhich the=e1ectrodes oftheprecipitat'or are beingsprayed with cleaningfiuid;

It is a. further objectofi'the'invention to :provide; a" control 1system of." the: type" described in which the entire cleaning: operationbecomes automatic" upon the actuation of aswitch by the; operator,. andin which the-washing zand drying process will proceed; be accuratelytimed, and the precipitator returned to its normaloperationuponcompletions of the process without; further attention onthe part of theoperator.

The foregoing and'toth'er: objects" and featuresof the invention will bemadefully apparent to those skilled in the art from a consideration ofthe following detaileddescription; taken incona junction with theaccompanying drawings in WhlChZ Fig. 1 is a perspective view; with partsbroken. away to show internal vconstruction, .ofa combined aircl'eaningand heating system; and

Fig. 2is a schematic.viewshowinglanelectricala control system forcombined" air cleaning and heating systems in accordancewith theinvention. Referring to the drawings, referencenumeral Ill indicatesgenerally aprecipitator'which may,.

for example, be of 'the" type disclosedin my co.-

pending applicationpreviously mentioned; The; air to be purified-isforced through the precipitator: ID by means of a fan I l and the air isthen passed through a conduit l2 into heat'absorbingrelation'. to afurnace 53 from which .the air. passes through: Y a hot airsupply duct Il-to the air distributingi system.

65- water-,- with or 'Without soap .or r other: detergents;

is supplied by way of a supply pipe l5 controlled by a solenoid valve l6. Upon the opening of the solenoid valve IS, the water is suppliedunder pressure to a manifold ll positioned above the ionizing electrodes8 and I3 and collecting e1ectrodes 9 and I9. Manifold I! is providedwith a plurality of spray nozzles 20 directed toward the electrodes 8,l8 and 9, I9 in a manner to cause the cleaning fluid to impinge upon allparts of said electrodes.

In such a system, if the washing operation is left to the discretion ofthe operator, it is possible that the power supply'for the energizationof the electrodes will be left on'at the time the solenoid valve I6 isenergized to the detriment of the system. Also the operator might failto cut off the power supply to the fan H prior to the initiation of thecleaning operation. In this event much of the spray from the nozzles 20would be blown into the conduits of the heating and ventilating system,or be discharged from this system into the living quarters of the house,instead of falling to the collecting sump at the bottom of theprecipitator. Other errors could be made such as failing to let theelectrodes 8, l8 and 9, I 9 dry after the spraying operation, beforeturning on the power supply to energize the electrodes. Also it would beundesirable to continue the fuel supply to the oil burner 21 of thefurnace when the fan H is not in operation. Such errors are avoided andthe operation made completely automatic by the control system shown inFig. 2.

Referring to Fig. 2, a motor 22 has its shaft connected to the drivingshaft of a speed reduction gear 23 having a drivenshaft 24. A pair ofcams 25 and 2B are mounted upon the shaft 24 to be driven at a very lowspeed through the reduction gear 23. For example, one revolution of theshaft 24 may require approximately twenty minutes. Cam 25 has an activeportion 21, which active portion extends for only a few degrees of theangular movement of the cam, for example about four degrees. The activeportion 21 actuates a rod 28 against the action of a spring 29. The cam26 has an active portion 3!, which active portion extends oversubstantially 270 degrees of the circumference cam. The active portion3| of the cam 26 is adapted to actuate a rod 32 against the action of aspring 33. The rod 28 controls a pair of normally closed contacts 34 andtwo pairs of normally open contacts 35 and 35. By the term normally Irefer to the position of the mechanism as shown in Fig. 2, which is thestate of the system when the precipitator and the furnace are performingtheir normal functions of cleaning and heating the air forcedtherethrough by the fan I I rather than to the condition in which thesefunctions are discontinued to permit the cleaning of the collectingelectrodes of the precipitator. The rod 32 controls a pair of normallyclosed contacts 31 and a pair of normally open contacts 38. In theposition shown, a circuit is provided across the terminals l and 2 of asource of power supply, which circuit comprises the conductors 4| and42, the closed contacts 31, conductor 43, fan switch 44, conductor 45,closed contacts 34, conductor 46, the primary winding 41 of atransformer 48, and conductor 50 leading to terminal 2. The secondarywinding 49 of the transformer 48 is connected across the energizingcircuit of the electrodes l8 and 19. The fan motor II is connectedacross the conductors 45 and 50. Thus, assuming that the fan switch 44,which is actuated by a thermostat in the bonnet or hot air reservoir ofthe furnace, is closed, the precipitator electrodes 8, I8 and 9, l9 willbe energized, the heat control system of the furnace will be inoperation, and a circuit will be closed thorugh the fan motor II toforce air through the system.

The power supply circuit for energizing the electrodes is more fully setforth in my copending application, Serial No. 692,893, filed August 24,1946, now Patent No. 2,476,247, dated July 12, 1949. As shown, thesystem comprises a pair of rectifier tubes 52 and 53 connected ininverse relation to' one terminal of the secondary winding 49. The otherterminal of the secondary winding 49 is connected through a conductor 54to ground. The tube 52 has its cathode con nected by way of a conductor55 to the fine wire electrodes :8 of the ionizing means. The tube 53 hasits anode connected by a conductor 56 to the surface electrodes 8 of theionizing means and to the charge electrodes IQ of the collecting system.The charge electrodes I 9 are alternate plates of the collecting system,the intervening plates 9 of which are connected to ground. A condenser51 and a resistor 58 are connected between the conductor 54 and theconductor 55. A resistor 59 is connected between the conductor 54 andthe conductor 56.

The operation of the power supply system described in the foregoing ismore fully set forth in my copending application, Serial No. 692,893,filed August 24, 19%. It is suificient for the present purpose to notethat the line 55 will be maintained at a predetermined positivepotential of the order of 6 kv. Line 56 will be maintained at a negativepotential of 6 kv and accordingly the potential difference between thefine wire electrodes [8 and the surface electrodes 8 which are connectedto the line 55 will be of the order of 12 kv. The difference inpotential between the collecting plates l9 which are connected to line56 and intervening plates 9 which are connected to ground will be 6 kv.

When the parts are in the position shown, the circuit through the timingmotor 22 is open and accordingly the cams 25 and 26 are at rest. Thecircuit for the motor 22 from the terminal I of the source of supplyincludes the conductor 4!, a conductor 65, the contacts 36, and aconductor 66 connected to one terminal of the motor 22, the oppositeterminal of which motor is connected to the conductor 59 and accordinglyto the terminal 2. This circuit is normally open at the contacts 36. Apush button switch 61 between the conductors 65 and 66 may be actuatedby the operator to close a circuit by-passing the open contacts 36. Whenthe push button switch 8'! is closed, the motor 22 then drives the cams25 and 26 very slowly in a clockwise direction through the speedreducing gear 23. Within a few seconds after the closure of the switch6?, for example for about ten seconds, the active portion 21 of the cam25 will disengage the rod 28, permitting the rod to move upwardly,opening the contacts 34 and closing the contacts 35 and 36. The closureof the contacts 36 permits the operator to release the push buttonswitch 67 and the circuit through the motor 22 will remain closedthrough said contacts 35. Preferably a neon lamp 68, connected acrossthe motor 22, is provided to visually indicate to the operator that thecircuit through the motor 22 is closed. If the operator releases thepush button 61 before the contacts 36 have been closed, the lamp (i8will be acuums extinguished. The operator:" will again depress the pushbutton flvfor' 'ai few; seconds until the lamp 68 continues to= glow'upon the' release' of the push button, }-'iridicating that 'the wcircuit 1 through the contacts 35 is closed. At the instant the contacts36 are closed-"to-maintain a'circuit through the motor- 22, contacts 3dare -opened cutting off the power supply to the ionizing "and collectingelectrodes of the aprecipitator. "Simultaneously the contacts 35" areclosed. These contacts 35 close a circuit bypassing the switch-M itator,as for example in the condenser 51': or in the 1 capacitance'providedbythe collector plates l9,':to leak off or be dissipated through theresistorsf'58 and 59 before the introduction of cleaning fiuid into the,precipitator. .Byfthe endofjthis'peridd of twenty seconds the cam 26 hasrotated through a sufficient angle in a clockwise. directionso that theactive portion 3| of the camno longer holds the rod 32, inthe positionshown butppermits. the

rod to move upward1y,.loreaking the contacts 31 p .and closing thecontacts. 38. The opening of the contacts 31- opens the circuit whichdurin'gsthe previous twenty seconds permitted the. fiowW-of energy tothe fanmotor l I through therconductor 42, the contacts 31; thecontacts35, andthe conductor 45. Thus the iancan 1no 'longerforoe airthrough the precipitator. The circuit through the heat control systemisalso broken. :Itwillrbe understood that the heat control systemiwillinclude the means. for controlling thesupplyrofiuel to the oil burner:and any limitswitcheseor thermostatic .deviceszcapable ofnormally-controlling the supplyof fuel to the burner.

The closure of the'contacts 38"closes'"a'- circuit from the conductor-42 through a conductor l-fl leading to the energizing coilll ofthes'olen'oid valve 16 and thence byway ofconductor 1 2 and conductor 58to the-terminal '2 *of the'supply source. The energizationof the coil-"H "opens the valve 16, permitting cleaning 'fluidfrom the j.

pipe 5 to' besprayed'upon the ionizing'and collecting electrodes 'ofthepre'cipitator. I

The cleaningfiuidwill continue'to bespraye'd upon the electrodes foraperiod or approximately five minutes, while'the cam 26 rotates throughan angle :of approximately 90 degrees. At the end of this five-minuteperiod, the active portion 3| of the cam 26 again engages'the rod 32 toactuate this rod downwardly, breaking the contacts 38' and againclosing'the'contacts 31. The circuit through the coil H being broken,the valve [6 closes, and cleaning fluid is no'ilong'er sprayed upon'thecollecting" electrodes. Thezclosure of the contacts "'31 now closesa-circu-it through thefan motor Hby way or the contacts 35 which areclosed at this time so that the circuit through the fan is closedregardless of the position of the fan motor switch 44. A circuit alsoexists at this time from the terminal I through the conductor 42, thecontacts 31 and "ass "minutes.

: conductor-1143 through the zheat control system permitting-theoil'burner or the furnace to again she :placed in operation under thecontrol of the 'usual thermostaticdevices. The fan motor thus forces airthrough" the-precipitator while the power supply'to' the ionizing andcollecting electrodes remains broken *at' the contacts" 34. "Thiscondition continues while the cams 25 and'26 *rotate through'an'angle'of approximately 265 degre'es, and requiring approximatelyfifteen K At the end of-this fifteen-minute" period," the active portion21 of the'cam 25 again contacts the rod"28to'efiect the closure or thecontacts 34"andthe' opening of the contacts 35 and 36. The'partsarethusback in the'positionshown'in'Fig 2of the'drawings. The circuitthroughthexhbtot '22 being broken, the cams 25arid 26 come to rest.'Thus' the 'system is again' in its normal operative 'stategpoWer be-"ing'supplied to the tran'sform'er 48 of the precipitatorpower supplyprovided the" fan switch '44::is closed.

From" the foregoing itwill be apparent that the invention. providesacontrol system in which 'theentire cleaning operation is conductedautomaticall'y'inra manner to .assure that the sequence or. operationswill occur in -the desired order.

, :{While there has. been herein described a. preferredembodimentaofiithe. invention, other em bodiments .within the scope of.the appended claims will be app'arent to those skilled in the -art fromaconsideration :of the form show-n and the teachings hereof.

What is. claimed is:

1. An 1.- air a cleaning 1? and heating system comprising ans-electricaldustprecipitator, a furnace, aheat.controlrsystemior said furnace, a fanfor 'fforcing: air through said precipitatorlfor separating particulatematter therefrom, means conductingzsaid air from said precipitator inheat absorbing relation to said furnace, washing means to cleandepositsI of particulate matter from said precipitatonand means effective upontheroperation of said washing means to stop the operation of.-said.fan-and render said heat controllmeansinoperative to-cfiectthelsupply offuel to said furnace, and amotor-driven-timingsystem -for cdeenergizingrsaid i electrical dust pre- .cipitator 'a shortfixed-time prior totheinitiation of operationiofthe washing means.

2..A control system for electrical dust precipitators of.the typeincluding a plurality of ionizing and. collectingelectrodes, a, powersupply circuit for energizingsaid electrodes, and means forwashing saidelectrodes. in .situ, comprising a timingv motor, .7 a I manuallycontrolled switch for initiating the operation 'of said motor, anormally =open circuit =by-passing said manually controlled :switch, afirst switching mechanism operated by said timing motor for opening saidpower supplycircuit iand simultaneously closing said-normallyopencirouit to maintain said motor: inoperation regardless of. theposition of said manually controlled .switch, .a second switchingmechanism:operated'xby said timing rnotor' after'aJpredetrminedtime-idelay fromzthe opening of said poweri-supplycircuitzior supplying cleaning fluid. to saidwashing means for apredetermined 7'6 M e, said; first isvvitching :mechanism' beingeffective to again close said power supply circuit and stop said motorafter a predetermined interval from the termination of said supply ofcleaning fluid.

3. In an air heating and cleaning system comprising a dust precipitator,a furnace, a heat control system for said furnace, a fan for blow- 'ingair through said precipitator for separating particulate mattertherefrom, and into heatabsorbing relation with said furnace, a heatcontrol switch for controlling said fan, washing means to clean depositsof particulate matter from said precipitator, a motor-driven timingsystem for controlling the operation of said washing means, a switchoperated by said timing system for deenergizing said fan and said heatcontrol during the operation of said Washing means, and a switchoperated by said timing sys tem for positively energizing said fan,regardless of the position of said heat controlled fan switch, for apredetermined time immediately following cessation of operation of saidwashing means.

4. In an air heating and cleaningsystem comprising a dust precipitator,a furnace, a heat control system for said furnace, a fan for blowing airthrough said precipitator for separating particulate matter therefrom,and into heat-absorbing relation with said furnace, a heat controlswitch for controlling said fan, washing means to clean deposits ofparticulate matter from said precipitator, a motor-driven timing systemfor controlling the operation of said washing means, a switch operatedby said timing system for deenergizing said fan and said heat controlduring the operation of said washing means, and a switch operated bysaid timing system for positively energizing said fan, regardless of theposition of said heat controlled fan switch, for a predetermined timeimmediately following cessation of operation of said washing means, anda power supply for application of voltage to the plates of saidprecipitator, and a switch controlled by said timing system fordeenergizing said power supply a short fixed time previous to theinitiation of said washing operation to allow the precipitator plates todischarge to a low value.

5. In an air heating and cleaning system comprising a dust precipitator,a furnace, a heat control system for said furnace, a fan for blowing airthrough said precipitator for separating particulate matter therefrom,and into heat-absorbing relation with said furnace, a heat controlswitch for controlling said fan, washing means to clean deposits ofparticulate matter from said precipitator, a motor-driven timing systemfor controlling the operation of said washing means, a switch operatedby said timing system for deenergizing said fan and said heat controlduring the operation of said washing means, and a switch operated bysaid timing system for positively energizing said fan, regardless of theposition of said heat controlled fan switch, for a predetermined timeimmediately following cessation of operation of said washing means, anda power supply for application of voltage to the plates of saidprecipitator, and a switch controlled by said timing system fordeenergizing said power supply a short fixed time previous to theinitiation of said washing operation to allow the precipitator plates todischarge to a low value, and said fan being energized during the periodwhen said source of voltage is being deenergized.

6. In an air heating and cleaning system comprising a dust precipitator,a furnace, a heat control system for said furnace, a fan for blowing airthrough said precipitator for separating particulate matter therefrom,and into heat-absorbing relation with said furnace, a heat controlswitch for controlling said fan, washing means to clean deposits ofparticulate matter from said precipitator, a motor-driven timing systemfor controlling the operation of said washing means, a switch operatedby said timing system for deenergizing said fan and said heat controlduring the operation of said washing means, and a switch operated bysaid timing system for positively energizing said fan, regardless of theposition of said heat controlled fan switch, for a predetermined timeimmediately following cessation of operation of said washing means, anda power supply for application of voltage to the plates of saidprecipitator, and a switch controlled by said timing system fordeenergizing said power supply a short fixed time previous to theinitiation of said washing operation to allow the precipitator plates todischarge to a low value, and said fan being energized during the periodwhen said source of voltage is being deenergized, and a manuallyoperated push button switch for initiating the automatic sequencing ofthe entire cleaning operation by the timing system.

7. In an air heating and cleaning system comprising a dust precipitator,a furnace, a heat control system for said furnace, a fan for blowing airthrough said precipitator for separating particulate matter therefrom,and into heat-absorbing relation with said furnace, a heat controlswitch for controlling said fan, washing means to clean deposits ofparticulate matter from said precipitator, a motor-driven timing systemfor controlling the operation of said washing means, a switch operatedby said timing system for deenergizing said fan and said heat controlduring the operation of said washing means, and a switch operated bysaid timing system for positively energizing said fan, regardless of theposition of said heat controlled fan switch, for a predetermined timeimmediately following cessation of operation of said washing means, anda power supply for application of voltage to the plates of saidprecipitator, and a switch controlled by said timing system fordeenergizing said power supply a short fixed time previous to theinitiation of said washing operation to allow the precipitator plates todischarge to a low value, and said fan being energized during the periodwhen said source of voltage is being deenergized, and a manuallyoperated push button switch for initiating the automatic sequencing ofthe entire cleaning operation by the timing system, and an indicatingdevice associated with said timing system for indicating when saidtiming system is in operation.

KENNETH W. MACKENZIE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,233,639 Pegg Mar. 4, 19412,255,677 Penney Sept. 9, 1941 2,333,551 Pegg Nov. 2, 1943

